A polymer of hexafluoropropylene oxide (HFPO) can possess various groups at its terminals depending on the types of polymerization initiators used during the polymerization process. For example, HFPO polymers with the following groups at the ends of their molecular chains, i.e., terminals, are already known: CF.sub.3 --, CF.sub.3 (CF.sub.2).sub.4 --, (CF.sub.3).sub.2 CF--, (CF.sub.3).sub.2 CF--CF(CF.sub.3)--, FSO.sub.2 --, CH.sub.3 S--, CH.sub.3 OCO--, and ICF.sub.2 --. The HFPO copolymers having these groups are reviewed in Angew. Chem. Int. Ed. Engl., 24, 161 (1985).
Further, carbonyl fluoride (U.S. Pat. No. 3,114,778), perfluoropentanoyl fluoride (DE-OS 2,614,333), hexafluoroacetone (U.S. Pat. No. 3,274,239), and perfluoromethyl isopropyl ketone (U.S. Pat. No. 3,274,239) have been used as the initiators. The HFPO polymers obtained by using these initiators are expressed by the formula below: EQU Rf'--O--(Y).sub.p --CF(CF.sub.3)--COF
Wherein Rf' is a perfluoroalkyl group, Y is the HFPO unit expressed by --CF(CF.sub.3)--CF.sub.2 O--, and p is either 0 or a positive integer. On one terminal of the molecular chain (the opposite terminal from the side where the--COF group is connected) is the perfluoroalkyl group, which is a non-functional group.
Further, HFPO polymers with a functional group introduced at one end of their molecular chains by utilizing specific acid fluorides as an initiator are also known. For example, British Patent No. 2,053,902 shows an example which utilizes FSO.sub.2 --CF.sub.2 --CF.sub.2 --COF as an initiator and the HFPO polymer obtained in this case is expressed by the formula below: EQU FSO.sub.2 --CF.sub.2 --CF.sub.2 --CF.sub.2 --CF.sub.2 --O--(Y).sub.p --CF(CF.sub.3)--COF,
wherein Y and p are same as described above. This compound is understood as a hetero-bifunctional polymer with a functional group (--FSO.sub.2) introduced at one end of the molecular chain. Various other initiators which lead to the hetero-bifunctional polymers are also known and examples thereof are:
______________________________________ CH.sub.3 S--(CF.sub.2).sub.3 --COF (British Patent 2,051,831), CH.sub.3 OOC--(CF.sub.2).sub.4 --COF (DE-OS 2,708,677), and I--CF.sub.2 --COF (U.S. Pat. No. 3,311,658). ______________________________________
However, HFPO compounds and polymers with a vinyl group introduced as a terminal functional group at the end of the molecular chain have not been reported. The terminal functional groups of the known HFPO compounds and polymers do not include vinyl groups. Such compounds and polymers without terminal vinyl groups are incapable of combining with silicone compounds through hydrosilyation, which limits their use in the field of silicone chemistry.
On the other hand, a compound expressed by the equation below is known to possess a vinyl group: EQU CH.sub.2 =CH--CH.sub.2 O--CF.sub.2 --(Z)--COF,
wherein Z is --CF(CF.sub.3)--OCF.sub.2 --CF.sub.2 O--CF(CF.sub.3)--. This compound has a similar but distinct molecular structure to that of an HFPO polymer having a vinyl group at one end of the molecular chain. However, this compound is prepared through the reaction of a compound which possesses two--COF groups, expressed by the equation below: EQU FOC--(Z)--COF,
wherein Z is same as described above, with allyl bromide in the presence of cesium fluoride. This reaction has problems, both by offering a poor selectivity of products and by producing diallyl compounds as by-products.
Therefore, an object of this invention is to provide HFPO compounds and polymers having a vinyl group at their terminal end, and a manufacturing method thereof.
It is a further object to provide a novel vinyl group containing compounds useful as intermediates for the HFPO compounds or polymers.
Upon further study of the specification and appended claims, further objects and advantages of this invention will become apparent to those skilled in the art.